﻿1 8 TRUNCIIJ.A "• 



erals short, dttublc in the left valve, single in the right ; nacre 

 white; muscle scars well ini))resse(l. The only specimen seen, 

 the type, is a female which has a scarcely swollen marsupial 

 area, which is thinner than the rest of the shell and excavated 

 within. 



Length 22, height 16.5, diam. 13 mm. 



Type locality, Othcalooga Creek, Gordon County, Georgia. 

 Uiiio otlicaloogensis Li5a. Proc. Acad. Nat. Sci. Phila. IX^ 



^857, p. 32; Jl. Ac. Nat. Sci. Phila., I\\ 1858, p. 74, pi. xiv, 



fig. 54; Obs., VI, 1858, p. 74. pi. XIV. fig. 54. 

 Margaron (Unio) othcaloogensis Lea, Syn. 1870, \). 38. 

 TriinciUa othcaloogensis Simtsion, Syn., igoo, p. 521. 



It is possible that this may he a young female of T. haysiana^ 

 but I do not think it is. All the females I have seen of that 

 species have the marsupial area considerably more swollen 

 than it is in this shell, it is differently shaped, being higher in 

 front, and with the posterior end decidedly sculptured, while 

 the sculpture on this specimen is scarcely visible. This shell 

 has no radial furrow in front of the marsupial swelling, it is 

 differently colored from hoysiona, is more elongated and has 

 a white nacre. 



Subgenus Dysnomia Agassiz, 185.'. 



Dysnomia Agassiz, Arch, fiir Naturg., I, 1852, p. 43. 



Shell of the male with a posterior and central radiating 

 ridge, with a wide, flattened space between ; that of the female 

 with a greatly produced inflation, which is but little behind 

 the center of the base and which is a continuation of the cen- 

 tral ridge. Animal with the mantle beautifully maculate on 

 its border ; female animal unknown. 



Type : Unio foliatus Hildreth. 



TkUNCiij.A FOLiATA (Hildreth). 



Shell solid, but slightly inflated, subrhomboid or sub(iuad- 

 rate, nearly equilateral ; beaks somewhat elevated, subcom- 

 pressed, elongated, with very faint, slightly corrugated sculp- 

 ture : posterior ridge well developed, narrowly rounded, some- 



